The present Invention is directed to a circuit board assembly for enclosure in an electrical connection box. The Invention is more particularly directed to an internal circuit assembly in a lattice configuration with vertical or horizontal busbars or wires connected to each other directly and by means of solderless terminals. The Invention will be described with reference to an automobile circuit board, but it is not to be limited thereto.
In the past, busbars formed from conductive metal plates have been stamped in the shape of the desired circuit by using a die. Such circuits have been used as the wiring means for, in particular, automotive junction boxes. Alternatively, in place of the busbars, wires have been laid along circuits on an insulative plate, with solderless terminals being fixed to these wires to form solderless connections.
When busbars are used, a vertical busbar is bent from a conductive metal plate into the shape of the desired circuit and is aligned with the circuit on an insulative plate. The wires are preferably solid core and are laid along the circuit on the insulative circuit board and the solderless terminals are fixed to the wires to provide good electrical contact.
However, when circuitry of the foregoing type is provided, a die must be produced based upon each particular circuit desired. As a result, changes in the circuit are both difficult and costly to implement. Moreover, recent trends towards increased numbers of electronic parts has engendered a rapid increase in the number of circuits to be contained within the electrical connection boxes. It is often necessary to have seven or eight horizontal busbars disposed in multiple layers with insulative plates interposed. This leads to larger size and increased costs.
Moreover, the larger number of circuits requires complicated designs for the insulative plates on which the wires or busbars are placed. This makes the production of the insulative plates time-consuming and, in addition, requires substantial investments for the equipment necessary. When vertical busbars are used, they are formed integrally with tabs for connections to external circuits.
Thus, the busbars must be stamped with dies and, after this step is complete, must then be bent into the shape of the circuits. This increases the number of processing steps and further adds to the expense and difficulty in making any changes.
In an attempt to solve these problems, a number of structures have been proposed. Japanese OPI 60-35911 suggests the electrical connection box as shown in FIGS. 12(A), 12(B), 12(C), and 12(D). Unit case 1 is formed of lattice-shaped insulative material. Lateral conductive wires 3 and longitudinal conductive wires 4 have upside-down U-shaped cross-sections. At appropriate intersections, L-shaped solderless terminals 2 and tabbed solderless terminals 5 are engaged and connected to lateral conductive wires 3 and longitudinal conductive wires 4 to form the desired circuitry.
With the foregoing structure, circuits are formed by using solderless terminals 2 and 5 to connect the lateral and longitudinal conductive wires 3 and 4. Thus, circuit changes can be easily implemented simply by changing the positions of the solderless terminals. However, the lateral and longitudinal conductive wires are formed with the unique U-shaped cross sections which do not permit the use of standard solid core wires and also add to the cost. Moreover, wires 3 and 4 tend to deform when a load is applied, so that the opening of the U-shape is narrowed. Once this takes place, the connection between solderless terminals 2 and 5 and lateral and longitudinal conductive wires 3 and 4 becomes loose, whereby reliable electrical contact is not maintained.
Another attempt at solving the foregoing problems is to be found in Japanese OPI 56-130989. As shown in FIG. 23(A) and 23(B), circuit board 30, intended to be enclosed in an electrical connection box (not shown), is provided with stamped sections 33 which are stamped out of a conductive metal plate to form conductive lattice 34. Insulative sheets 32 are laminated on either side of the conductive lattice. To connect circuit board 30 with external circuits, wires are connected to the perimeter of conductive lattice 34.
In this structure, the circuits are formed by cutting out unneeded sections 37. Changes in such circuits can be implemented without undue difficulty, but there is no improvement in yield for the conductive metal plate, since the circuit is formed by stamping and there are many stamped sections 33. Wires can only be connected to the perimeter of conductive lattice 34; thus, the external circuits cannot be directly electrically linked to inner portions thereof. As a result, the connections are both complex and inefficient.
A further attempt to solve the foregoing problems is to be found in Japanese OPI 60-35912 as shown in FIGS. 34(A), 34(B), and 34(C). The insulative plate is in the form of unit case 1 which comprises lateral and longitudinal frames 61 and 62 which intersect each other at approximately right angles. Similarly, lateral and longitudinal conductors 63 and 64 also intersect on unit case 1. L-shaped solderless terminals 65 and 67 are inserted into the lateral and longitudinal conductors at prescribed intersections to form the desired circuit. External wire 66 is connected to this circuit through a solderless connection between conductor 63 and solderless connection blade 68 at the tip of solderless terminal 67 connected to the end of external wire 66.
This structure permits sharing of the insulative plate, but the plate must be assembled as a lateral/longitudinal frame and the wire guide cavities must be disposed throughout the frame. As a result, the structure becomes large and complex, increasing its cost and requiring a larger electrical connection box to enclose it. Also, in order to make the desired connections to the external circuit, solderless terminal 67, connected to external wire 66, is directly connected to the conductor. Thus, the external wire cannot be connected once the electrical connection box has been assembled.
It is the object of the present Invention to overcome the foregoing defects of the prior art. More specifically, it is intended to provide a solderless connection device for an internal circuit in an electrical connection box, while allowing the circuit to be formed easily and altered without major expense.
A circuit board assembly is provided which is particularly adapted forxe2x80x94although not limited toxe2x80x94enclosure in an electrical connection box for automotive use. There is a first plurality of lateral busbars substantially parallel to each other, as well as a second plurality of longitudinal busbars, also substantially parallel to each other. The two pluralities intersect each other, preferably at substantially right angles. A third plurality of slits is provided on the lateral busbars, and a fourth plurality of slits is on the longitudinal busbars. Each set of slits engages the other, at at least some points at which the lateral and longitudinal busbars intersect. Any portions of the busbars which are unnecessary to the circuits desired are cut away, thereby forming the conductive member. This member rests on one surface of a planar insulative plate. There is a fifth plurality of solderless terminals in electrical contact with predetermined positions on the conductive member.
It has been found preferable to have a pair of slits, one on each of the lateral and longitudinal busbars, at each of the intersections. It is further desirable to provide lattice grooves in the insulative plate so that at least a portion of the conductive member can be embedded therein. The insulative plate is. also desirably provided with one or more insertion grooves, each adapted to receive one of the solderless terminals. There is also at least one cutting groove into which a cutting tool may be inserted in order to cut away unneeded portions of the conductive member. These grooves usefully intersect the lattice grooves at substantially a 90xc2x0 angle thereto.
The solderless terminals include both terminal plates and jumper terminals. Each of the former has a tab at one end and solderless connection blades at the other end. The jumper terminals are similar, but are provided with solderless connection blades at both ends. The insulative plate is capable of receiving the solderless terminals from either or both sides, thereby forming good electrical contacts.
It has been found especially useful to adjust the pitches of both the lateral and longitudinal busbars. In other words, the distances between adjacent busbars of each type are varied so as to correspond to the terminal opening pitches for the various electrical elements to which the busbars are to be connected. Also, it is advantageous to provide a power supply connection busbar stacked on the circuit board. The entire unit, of course, fits within an electrical connection box and is of relatively small size, considering the number and complexity of the circuitry provided.
The lateral and longitudinal busbars can be in the form of substantially identical-shaped flat horizontal or vertical strips having electrical continuity at their intersection points. The lattice-shaped conductive member formed thereby has sections not required for circuits cut away.
There is an insulative film covering each surface of the conductive material in order to prevent unwanted electrical contact. Terminal openings in the insulated film and optionally in the conductive member have terminal plates extending therethrough, so that one end of the terminal plate is in fixed electrical contact with the conductive member. The other end of the terminal plate is a tab adapted to act as the external connection terminal. It may also be a jumper terminal wherein solderless connection blades are at both ends and in contact with other layers of conductor members.
The bonding of the lateral and longitudinal busbars is not critical, but welding, fusing, or riveting have been found satisfactory. Similar, the terminal plates are connected to the conductive member (lateral and longitudinal busbars) by soldering, welding, riveting, or fusing.
Preferably, there is a plurality of conductive materials (with insulative film covering) stacked vertically. Adjacent conductive materials are electrically connected as is appropriate by way of terminal plates or jumper terminals. These connections can also be made by welding or fusing adjacent conductive members to each other through the terminal openings in the insulative films.
Here, too, the lateral and longitudinal busbars are each spaced apart from their adjacent busbars at prescribed and predetermined pitches. These pitches correspond to the terminal opening pitches for the various electrical elements to which the busbars are to be connected. The power supply connection busbar, as in the previous cases, is usefully stacked on one of the insulated films.
A desirable form of the Invention essentially substitutes wires for at least some of the busbars previously described. First and second pluralities of lateral and longitudinal wires are provided. The lateral wires are substantially parallel to each other as are the longitudinal wires. The first plurality is layered on the second plurality so that they meet each other at intersection points, thereby forming the conductive member. The member is fixed on a generally planar insulative plate and the sections of the material which are unnecessary for the circuits are cut away. The usual solderless terminals are fixed to the lateral wires and the longitudinal wires at positions predetermined by the desired circuitry. The conductive member may be covered on both sides by insulative film.
Terminal plates, with a tab at one end and connection blades at the other end, and jumper terminals, having connection blades at both ends, are used to interconnect two or more layers of conductive material with each other; they also make contact with external circuits. The terminals can be inserted from either or both sides of the insulative plate.
As in the other configurations, it is particularly desirable if the pitches of the lateral and longitudinal wires are such that they correspond to the terminal opening pitches for the various electrical elements to which connection is to be made. Also, the power supply connection busbar can be stacked on the circuit board.